【 Weak current college 】 building automatic control system overview

Building automation system (BAS) is building technology, automatic control and computer network technology, the building has a smart building characteristics. Modern building has a large number of electromechanical equipment, these devices more dispersed. There are many more, that is, the accused, monitoring, measurement, and up to a thousand points above; powder, that is, those devices in each floor and every corner. If you have a decentralized, local control, monitoring, and measurement is unimaginable. Adoption of building automation system, you can use the device, conserving energy, saving manpower, ensure the safe operation of equipment to enhance the building mechanical and electrical equipment of modern management, and create a safe, comfortable and convenient work environment and increase economic efficiency.

1.1.1 system design standards

Building automatic control system is via a central computer system network will be distributed in the monitoring area smart sub-station on site, complete centralized operation, management and decentralized control of a comprehensive monitoring system.

I. system target

The goal of building automation system is all about building mechanical and electrical equipment uses modern computer control technology for comprehensive and effective monitoring and management to ensure that all equipment in the building is efficient, safe and reliable running at optimum levels to better harness the potential of the building.

Second, the system design principles

In addition to meeting the owners of the "simple, practical, appropriate advance overall design principles", should meet the following principles:

L technology advanced, mature, functional practicality. The system uses the international standard communication protocol and bus technology that ensures system reliability, security, openness and interoperability.

L distributed design, modular construction, easily configurable, extended, for future expansion of the system with full room to upgrade.

L openness and compatibility is good, required system settings of the DDC is RS232/RS485 interface and standard protocols, to achieve its system software and hardware connections, the details of doing interface design, the system is fully open, tolerant, safe and reliable Exchange of information.

L extended functionality. Where measurement and control devices have automatic control features are to retain and use, the system and its online information exchange, monitoring, control and management.

L economic, energy, can significantly save energy, reduce maintenance, management, optimization of equipment operation. Man-machine interface is good, it is convenient to run management, realistic images, rich content and data accurate, responsive, simple operation, ease of development, all finished, have the historical data records, the label table statistics, program management and trends analysis capabilities on the building of the central air-conditioning system, elevator systems, water supply and sewerage system. Lighting and electrical systems for monitoring and management.

1.1.2 system designed

The civil construction electrical design code JGJ/T16-92


The heating, ventilation and air conditioning adjustable design code GBJ19-87

The automatic fire alarm system design code GBJ116-88

The intelligent building design standards (DBJ-08-47-95)

The terminus building intelligent control system design project tender document

Party a to provide the civil, electrical, air conditioning, water supply and drainage, fire, and other professional drawings

1.2 system features and technical requirements

Depending on the capabilities of tenders and the technical requirements of the project's actual situation, we plan to consider the design-time focus on the following basic functions:

L electromechanical equipment running monitoring function

L central air conditioning system and energy-saving function

L through the graphical software management maintain Visual

1.2.1BAS monitoring programme

The program is in strict accordance with the tender requirements set monitoring point and have a 20% margin. BAS configuration of monitoring points for a total of 752 point (for details, see the frontier office building at BAS points total table ") monitoring include:

2 central air conditioning system for monitoring, recording and control and regulation.

2 ventilation equipment for monitoring, recording and control.

2 lift system running status monitoring and recording.

2 drainage equipment, fire water system monitoring and logging and control.

2 electrical equipment operation of monitoring and recording.


2 lighting switch status monitoring, recording and control.

2 other systems of dry contacts of monitoring and recording.

A, central air conditioning and ventilation systems

This system of water chillers, cooling water system and cooling water systems, are all located in the underground air conditioning room on the second floor. Cooling towers and water tanks placed on the roofs, the air conditioning terminal equipment including air conditioning unit, new fans, exhaust ventilation, fan, etc., are located on each floor, more dispersed.

Chilled water and cooling water systems

Since chiller by air-conditioned vendors controller separately control, BAS using OPENLINK interface Q9200A and chiller control computer connected, read information about each unit, chillers, cooling water pumps, cooling towers, cooling water pumps and valves for monitoring. Monitor content as follows:

Chiller operation status, hand/automatic status, fault alarm and commitment control

The operational status of chilled water pumps, hand/automatic status, fault alarm and commitment control

Cooling water pump running, hand/automatic status, fault alarmAnd commitment control

Cooling fan running, hand/automatic status, fault alarm and commitment control

Cooling tower water valve switching State and switch control

Cooling water total for/return pipe temperature monitoring

Frozen water total for/return pipe temperature monitoring, water supply pipe flow monitoring.

Total for the chilled water back into the water pressure difference monitoring and by-pass

Chiller for cooling and freezing water flow monitoring

Cold water machine electric butterfly valve switching State and switch control

Cold water machine chilled water outlet temperature monitoring

Unit is powered by color graphics displays all devices running status, fault status, parameters, values and

Line parameters with the audio alarm, through the mouse can be arbitrary character set value, in order to achieve the best in the running state.

Unit every point in the list, the parameter values with trend display, alarm display and summary.

BAS workstations are available through the system settings of the emergency stop switch signals control the entire chiller emergency stop.

Can be run on the device for cumulative time

Control principles are as follows:

? The number control chillers:

By frozen water for water temperature difference and water flow out of frozen water system of cooling load, and according to the actual cooling load in a timely manner to adjust the input operation of chiller and the number of associated facilities in order to achieve the best power-saving state.

? Interlocking control:

In order to ensure that the chillers and related equipment in normal operations, control the start and stop the device will make the following order.

I. start: frozen water pump → cooling water pump → Tower → freezer

Ii. stop: freezer → freezing water pump → cooling water pump → cooling fan

Trouble connecting:?

Refrigeration system, each refrigeration/freezing water/cooling water pump/cooling towers each alternate. When any one device fails, the DDC controller stops the equipment and the equipment of the cumulative elapsed time, start the run-time minimum of similar equipment to ensure the continuous operation of the entire system.

Flow switch detection:?

When the system detects any one refrigerator cooling water or chilled water flow switch alarm will stop running on the machine, and put into another unit operation.

The by-pass valve pressure difference?:

Chilled water system water pressure difference between the total for the circuit and BA system of differential pressure setting value, the control of pressure differential bypass valve to open degree, to maintain a differential pressure of frozen water system at a reasonable level.

» Cooling tower fan start/stop control:

Cooling tower fan with hierarchical control programmes, and the cooling water return water temperature and BA system cooling water return temperature levels set value, the DDC controller determine cooling fan of the number of start/stop.

Optimal operation of building refrigeration control:

DDC controller under refrigeration units run cumulative time, every time you boot accumulated time at least one of the refrigeration unit, in order to achieve the balance of the unit operating time. BAS by integrating equipment and chiller control unit communications, the following data for detection and control:

Refrigeration load data;

Evaporator pressure too low/too high;

Oil pressure too low;

Condenser pressure too high;

Exhaust temperature is too high;

Oil temperature too high/too low;

Fluid temperature is too high;

Flow switch failure; water temperature is too low;

The water temperature is too low;

Line voltage too low;

AC voltage is too low;

Prevent duplicate start;

Thermocouple open circuit;

Evaporator of sensor failure;

Power failure;

Unit periodic downtime;

Air conditioning unit

The fresh air conditioning system, ventilation system and air supply system combination, we start by controlling fans, as well as control of chilled water valve, air supply valve and return air valve to open degree, to improve indoor air quality, achieve comfortable, energy-saving purposes. Due south of humid air, we at design time only focused on the regulation of temperature, humidity.

Control as follows:

The air conditioner is on or off?, fault alarm, manual/automatic status and switch control

? Return air temperature monitoring

Wind pressure of air supply pipe line monitoring

Outdoor temperature/humidity» monitoring

? Filter pressure monitoring

» Air valve and return air valve to open degree adjustable

Control principles are as follows:

? DDC controller to return air temperature PID control. By adjusting the frozen water two-way valve to open degree, return air temperature maintained at the set value ranges, when fan is stopped frozen water 2-way valve will be closed.

? According to outdoor air enthalpy throttling fresh air valves/air valve. Fresh air valves/air valve in the software set up of interlocking, while fresh air valve turn return air valve, and vice versa.

The pressure differential switch? will monitor the status of the filter when the filter blockage, the pressure differential switch signals, will be issued to urge the maintenance personnel to clean filters.

Fan running and building air valve interlocks, so when fan is stopped, it will completely turn off the air valve.

Fans can advance? compile time holiday program to control the start and stop

According to the outdoor temperature/? humidity values to adjust the air supply valve to open degree.

New fan

Control as follows:

? Air temperature monitoring.

New fan running, hand/automatic status, fault alarm and switch control.

? According to outdoor temperature to change the set value air temperature in order to save energy.

? DDC controller on air temperature PID control. By regulating cold water valve to open degree, so that the air temperature remains within the set value. When the fan is stopped, the cold water electric valve will be closed.

The pressure differential switch? will monitor the new fan filter condition, when the filter blockage, the pressure differential switch signals, will be issued to urge the maintenance personnel to clean filters.

Fan running and building air valve interlocks, so when fan is stopped, it will completely turn off the air valve.

? According to the hours set time control program.

And exhaust blower (air blower)

Control as follows:

Exhaust and smoke machines, buildings into the fan running, hand/automatic status, fault alarm and switch control.

Exhaust and smoke machines usually buildings under the basement of the CO concentration, CO2 concentration in the exhaust air for intermittent; fire, full control by the fire alarm system.

? According to the hours set time control program.

Second, water supply and drainage system

BAS system according to the building of the change of water consumption, timely adjustment of system life pump run number to reach the water supply and water demand balance between achieving the best running pump room, high efficiency, low energy consumption optimization control, so as to achieve the purpose of the operation.

According to water supply and sewerage preliminary design, all submersible pump may have a magnetic ball float liquid level controller control, the fire pump consists of a separate control of fire-fighting system, BAS system on submersible sewage pumps and pumps only prison does not control.

Monitor content as follows:

The living water tank, tank? high/low water level monitoring and alarm.

» Set the high water level monitoring wells and alarm.

? The operational status of living water pump, hand/automatic status, fault alarm and switch control.

? Submersible pump operation status, hand/automatic status, fault alarm.

? Fire hydrant pumps and spray pump running, hand/automatic status and fault alarm.